[Mesa-dev] intel, dma-buf import and egl image external

[Dave Airlie]

On Sat, Mar 8, 2014 at 12:13 AM, Pohjolainen, Topi
<topi.pohjolainen at intel.com> wrote:
> On Mon, Mar 03, 2014 at 01:19:48PM +1000, Dave Airlie wrote:
>> There is a comment and two checks in the i965 dma-buf importer,
>>
>> * Images originating via EGL_EXT_image_dma_buf_import can be used only
>> * with GL_OES_EGL_image_external only.
>>
>> however I can't find any reference to this in the spec txt, and
>> removing the checks make my test app run fine using TEXTURE_2D.
>
> You are correct that there is nothing in the spec about this, but it also leaves
> it open for the driver to choose on which buffers it allows the external
> sampling.
> After quite a bit of debate on when/where it would be safe to use dma-buffers,
> it was decided that we simply allow dma-buffers for external sampling only -
> that extension already restricts the use for single-miplevel and read-only
> which is exactly what we wanted.
> The same time it wasn't clear what kind of sources we should allow for external
> sampling (besides dma), and hence we simply kept things as they were before -
> none other. Note that before the introduction of dma-buffers the image external
> extension wasn't enabled at all on i965.
>

This is a really bad idea, since it means you can't use dma-buf
imported things with standard shader programs, if I want to import a
dma-buf I shouldn't have to write specific shader programs or use
special bindings, unless the spec says so.

Either the spec should be more restrictive, or the implementation
shouldn't have arbitrary differences from what other implementations
could do.

Dave.